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What can be learnt from oxygen isotopes composition of teak tree rings from India? Rainfall reconstruction up to AD 1743. Shreyas R. Managave Department.

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Presentation on theme: "What can be learnt from oxygen isotopes composition of teak tree rings from India? Rainfall reconstruction up to AD 1743. Shreyas R. Managave Department."— Presentation transcript:

1 What can be learnt from oxygen isotopes composition of teak tree rings from India? Rainfall reconstruction up to AD Shreyas R. Managave Department of Earth Sciences Pondicherry University, India Collaborators Prof. R. Ramesh, Physical Research Laboratory, Ahmedabad, India Dr. H. P. Borgaonkar, Indian Institute of Tropical Meteorology, Pune, India Dr. A. Bhattacharyya, Birbal Sahani Institute of Palaeobotany, Lucknow, India

2 Teak (Tectona grandis)

3  Chhattisgarh I  Chhattisgarh II  Kerala Jagadalpur Hanamkonda Perambikulum Sample Locations (1532 mm; 82 days, NE/SW=0.11) (940 mm, 53 days, NE/SW=0.17) (2163 mm, 102 days, NE/SW=0.27)

4 Objectives  To understand what governs isotopic composition of teak growing in different meteorological settings in India  To check whether trees growing in the southern part of India show isotopic signature of SW and NE monsoons  Reconstruction of high resolution past monsoon rainfall

5 Rationale behind the data interpretation

6 Amount effect and passage of water in plant  18 O rain Amount of rainfall 1Precipitation

7 H2OH2O CO 2 Importance of relative humidity Relatively 16 O enriched Relatively 18 O enriched 6CO 2 + 6H 2 O + sunlight = C 6 H 12 O 6 + 6O 2

8 Results from intra-ring studies Results from inter-ring studies

9 Results from intra-ring studies 1 ~Early growing season (May) 2-6 ~Main growing season (June-Sept) 7-8 ~Late growing season (Oct-Dec) Pith side Bark side time Tree from central India & southern India

10 Intra-ring  18 O analysis of teak sample from central India Coarse resolution studies High resolution studies June to Sept Oct-Dec Pith side Bark side 4mm time Sample location: Jagdalpur Managave et al., GRL 2010

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12 Relative humidity controls intra-annual  18 O variations Managave et al., GRL 2010

13 Break monsoons and intra-ring  18 O variations 3 to 17 days (average 5.8 days) (Ramamurthy, 1969) Goswami and Mohan, 2001; Gadgil and Joseph 2003

14 Break monsoons and relative humidity RainfallRelative humidity (Krishnamurthy and Biswas, 2006) Break monsoon over central India

15 Break monsoons and relative humidity Year with break-monsoon (19 th July to 3 rd Aug 1972 A.D.) Year with active monsoon (1 st Aug to 31 st Sept 1971 A.D.) Managave et al., GRL 2010

16 Location: Jagadalpur, Chattisgarh Intra-annual carbon and oxygen isotopic composition of teak Positive correlation indicates control of relative humidity

17 Intra-annual  18 O variations Location: Perambikulum, south India June to SeptOct-Dec Location: Jagadalpur, central India June to SeptOct-Dec Managave et al., Clim dyn 2011

18 Winter (NE) monsoon rain is depleted in 18 O Location: Kozhikode GNIP data

19 Modeled climatological  18 O profiles for Palakkad area  Trees from southern India samples both the SW (Jun-Sept) and NE (Oct-Dec) monsoons   18 O of whole ring is likely affected by (NE/SW) ratio Monthly weather data Palakkad (Rainfall, RH) ( ); & Kozhikode (  18 O) ( ) Climatological intra-ring  18 O profiles Managave et al., Clim dyn 2011

20 Significance of plants having signature of both the monsoons Spatial distribution of (  18 O summer –  18 O winter ) rainfall Araguas-Araguas et al., 1998

21 Summary of intra-ring studies  Teak from central India:  Relative humidity decides intra-ring  18 O variations  Time resolution: pre-, main- and post-monsoon  Possibility of detecting major break-monsoons  Teak from southern India:  Winter monsoon signature is preserved  Possibility of reconstructed both the monsoons using intra-ring studies  Care should be taken while interpreting annual  18 O variations

22 Results from inter-ring studies a)Tree from Jagadalpur, central India b)Tree from Perambikulum, southern India

23 Location: Jagadalpur, central India Sub-divisional rainfall  18 O (r = 0.5, P<0.005) Positive correlation between rainfall &  18 O Managave et al., Dendrochronologia, 2011

24 Why positive correlation between cell.  18 O and rainfall? Leaf area index Leaf area index Soil moisture Yoshifuji et al., 2003 data

25 Higher the length of growing season, more positive  18 O values Relative humidity conditions during monsoon and post-monsoon season Lower  18 O Higher  18 O

26 Location: Jagadalpur, Chattisgarh 5-yr running mean Comparison between two trees from Jagadalpur r=0.5 P<0.005 r=0.7 P<0.005 Managave et al., Dndrochronologia, 2011

27 Location: Perambikulum Kerala Negative correlation between rainfall &  18 O r = −0.5, p<0.005 Managave et al., Dndrochronologia, 2011

28 Temporally varying strength of correlation Managave et al., Dndrochronologia, 2011

29 Higher rainfall during the later part of the Little Ice Age Comparison with regional rainfall record Extended local and regional rainfall record by 128 and 70 years, respectively Managave et al., Dndrochronologia, 2011

30 Thank you

31 Other evidences of higher rainfall Borgaonkar et al., 2007 Bhattacharyya et al., 2007

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33 Observed and modeled Intra-ring  18 O variations  Models can be used to interpret intra-ring  18 O variations  Resolution of main- and post-monsoon season can be achieved  Possibility of achieving ~20 days of time resolution Jagdalpur sample Observed Ring = 1971 Modeled Daily weather, 1971,Jagadalpur Under review: Current Science

34 No amount effect By and large positive correlation between rainfall &  18 O (r = 0.4, P<0.005) % rainfall departure anomaly  18 O Location: Thane, western India Under review: Dendrochronologia


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